Monday, February 21, 2005


Metal Detectors

What Is A Metal Detector?

Metal detectors are electronic devices or instruments, which are capable of detecting the presence of metals and some minerals. They usually consist of a control box or electronic housing that is mounted to a rod, with a searchcoil attached to the other end of the rod. The rod or control box has a handle and the length of the rod is adjustable to the user's height. The searchcoil and control box are connected by an electronic cable. The control box contains most of the electronic circuits, various control knobs, batteries, speaker, headphone jack or calibrated meter. Metal detectors come in a variety of shapes, weight and sizes. There are also different types, each designed for a specific function or purpose.

How Do Metal Detectors Work?

In simple terms, the control box contains an electronic circuit called a transmitting oscillator. The control box battery supplies a current to the oscillator circuit, which produces an electronic signal. The signal generated is routed to the searchcoil by way of a connecting coax cable. The searchcoil also contains wire which is usually wound in the form of a circular coil. The searchcoil serves as a transmitting antenna. The transmitting antenna or searchcoil, builds up an electromagnetic field which is transmitted to a medium, such as the ground, air or even water. The generated electromagnetic field forms a field pattern. The presence of a conductive metal or mineral object, interferes and changes the characteristics of this pattern, to form smaller patterns around the object called eddy currents. The formation of these eddy currents move across the surface of the metallic object and result in a loss of signal level from the initial electromagnetic field pattern. The searchcoil has electronic circuits which detect the change in field pattern and routes this information back to the control box. The control box analyzes the searchcoil signal information and determines the probable identity of the object. The presence of the object, a piece of metal, mineral or coin for example, is conveyed to the operator by audio or visual meter signals.

What Type of Metal Detector Do You Need?

There are many brands of metal detectors available for treasure hunting. They may be specific for land only, water or both. Most land-use detectors have a water proof searchcoil but the control box is not usually waterproof. The cost of a metal detector varies greatly however. This is because specific features cost more. Features such as discrimination circuitry or programs pre-loaded for relic hunting, coins, jewelry, beach or gold. You don't need to spend a fortune for the best, although it's probably a waste of time to purchase one without a discrimination feature, unless you plan to only hunt in the all metals mode. Metal detectors with discrimination control, are able to weed out high levels of trash or junk encountered in a particular area being searched. They are capable of eliminating most trash items or pull-tabs and metal screw tops from various cans and bottles. This feature is important so that a treasure hunter is able to spend more time on digging valuable targets such as coins or other items of value. In any case, purchase the metal detector that suits the way you will hunt for treasure, with the features you need, at a price within your budget. There are many mail order catalogs and hobby stores available to purchase the one that's right for your needs.

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